Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Oregon should be reviewed to figure out when it's the best time to plant thunbergia.

Planting Calendar for Thunbergia

Frost tolerance for thunbergia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

It's not a good idea to plant thunbergia until after the last frost because they require warm weather.

The earliest that you can plant thunbergia in Oregon is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant thunbergia and expect a good harvest is probably August. If you wait any later than that and your thunbergia may not have a chance to grow to maturity. If you are starting your thunbergia indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Oregon the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -5°F.

Just be sure to remember that USDA zone info for Oregon is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Oregon last frost occurs after April 15 so always be ready to cover your thunbergia if you have a late frost.

USDA Zone Info for Oregon

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Oregon

You may be interested in your other planting guides for Oregon.